Chair

ABSTRACT

A seat that consists of a single-component body ( 1 ) includes an essentially horizontally arranged seat element ( 11 ), an upwardly projecting backrest ( 12 ) applied to the rear of the seat element ( 11 ), and two front legs ( 10,10′ ) extending at the front of the seat (11). The two separated rear legs ( 2 ′) are to be inserted and fixed in the body ( 1 ), the legs being provided with a non-rotationally symmetrical insertion part ( 22 ′). An externally accessible opening for positively inserting the insertion parts ( 22′ ) is provided on the body ( 1 ). The insertion parts ( 22 ′) and openings are provided with an enlarged surface in relation to the core diameters thereof. The insertion part ( 22 ′) is embodied as an insertion tenon ( 22 ′) extending from the rear leg ( 2 ′) and having an essentially elliptical cross-section which conically tapers off in the direction of the free end.

APPLICATION AREA OF THE INVENTION

The present invention relates to a chair which comprises a single-part body and fitted-on rear legs. The body comprises a seat which is arranged, in principle, horizontally, also comprises the backrest, which extends at the rear end of the seat, and further comprises the front legs, which curve downward in the corner regions of the front end of the seat and extend to the floor. The chair may be provided with or without armrests. The invention deals specifically with improving the stability of the chair design of the generic type.

PRIOR ART

International Design Registration DM/022613 discloses a chair of the type mentioned in the introduction in which a leg framework is screwed onto a single-part body—having a seat, backrest and front legs—beneath the body. Arranged on the central part of the leg framework, the central part connecting the rear legs, is a retaining plate which serves for screwing-on purposes beneath the seat. Separate, curved armrests are screwed on, on the one hand, on the rear side of the backrest and, on the other hand, beneath the seat. This design requires considerable material-related and installation-related outlay to produce. DE 202 19 476 U1 discloses a chair having a single-part body which comprises a horizontally arranged seat which merges, at the rear, into an upwardly projecting backrest. The front legs extend from the seat at the front in the direction of the floor. Provided beneath the body, in the side regions of the latter, is a plug-in mount which is accessible from the rear side of the chair and into which an extension on the rear leg can be plugged.

OBJECT OF THE INVENTION

Based on the prior art which is already known in this respect, the object of the invention is to propose a chair of the generic type defined in the introduction which has improved strength. The intention is for the chair to be capable of being mass-produced in an efficient manner with the lowest possible level of installation-related outlay and for it to be provided in designs with and without armrests.

OVERVIEW OF THE INVENTION

The chair has, as its most essential component, a single-part body which comprises:

-   -   a seat arranged, in principle, horizontally;     -   an upwardly projecting backrest extending from the seat at the         rear;     -   front legs extending from the seat to the floor at the front;         and     -   rear legs which are plugged into the body and extend to the         floor.

Each rear leg is present as a separate component and is provided with a plug-in part which is not rotationally symmetrical. An externally accessible opening into which the plug-in parts can be plugged in a form-fitting manner is present on the body, laterally in each case, in the region of the rear seat end. The plug-in parts and openings are provided with a surface area which is enlarged in relation to their core diameters.

The following features relate to specific embodiments of the invention: the plug-in part is designed as a plug-in stub which extends from the rear leg and is of, in principle, elliptical cross section, the cross section of the plug-in stub tapering conically in the direction of the free end. The openings have an, in principle, elliptical cross section which complements the plug-in stubs and widens in the direction of the inlet of the openings. The openings are oriented toward the sides of the chair. On their outer surface, the plug-in stubs have an encircling outer toothing formation which extends preferably in the axial direction of the plug-in stubs and openings. On their inner surface, the openings have an inner toothing formation which complements the outer toothing formation of the plug-in stubs.

A rear leg comprises:

-   -   an elongate leg support;     -   a curved connector extending at the top end of the leg support;         and     -   the plug-in stub, which adjoins the curved connector and is         arranged, in principle, horizontally in the plugged-in state.

In the case of the chair variant with armrests, the rear leg merges upward into an armrest. Such a rear leg comprises:

-   -   a connecting part which is designed as an extension of the leg         support and has its bottom end extending at the top end of the         leg support; and     -   a bottom armrest part which is attached to the top end of the         connecting part and is arranged, in principle, horizontally when         the rear leg is in the plugged-in state. A separate, top armrest         part is provided and is fastened on the bottom armrest part.

The seat is of shell-like design and has an upwardly projecting lateral wall periphery along each of its lateral boundaries. An upwardly projecting rear wall periphery is present along its rear boundary. The lateral wall peripheries merge into the rear wall periphery in each case over a preferably curved transition region. Arranged in the corner regions at the rear end, on the upwardly oriented side of the seat, are housing-like attachment parts which enclose the openings, which extend, in principle, parallel to the rear wall periphery. The attachment parts are bounded by a rear wall in the direction of the seat interior. The openings open out preferably into the transition regions between the lateral wall peripheries and the rear wall periphery. An externally accessible screwhole is provided in the rear wall. The plug-in stubs have an internal cavity, and projecting from the inner surface of the cavity is a convexity which is arranged longitudinally in relation to the axis of the plug-in stub. An internally threaded blind hole is provided in the convexity, the blind hole coinciding with the screwhole in the rear wall of the attachment part in the plugged-in state.

The chair has a unit-spaced rib formation arranged at the front end of the seat, on the upwardly oriented side thereof. This rib formation comprises, in the first instance, spaced-apart longitudinal ribs which are arranged, in principle, parallel to the front boundary of the seat and project upward with a forward slant. The rib formation also comprises spaced-apart transverse ribs which are arranged transversely to the longitudinal ribs and project upward from the seat.

The sandwich-construction cushion comprises:

-   -   a bottom sheet which is to be foamed onto the seat, extends         between the periphery and, during foaming, flows into first         interspaces formed between I spaced rib formation, is adjacent,         in the rearward direction, to the rear wall ateral wall         peripheries, reaches, in the forward direction, beyond the         unit-longitudinal ribs and transverse ribs;     -   a top sheet which is arranged, in principle, parallel to the         bottom sheet and, in principle, congruently therewith and, in         the rear corner regions, has a respecttive contour, in the         clearance between the attachment parts and seat, in which the         attachment parts are embedded; and     -   a cushion foam material which is introduced between the bottom         sheet and top sheet.

The seat has a through-passage at the rear end, and the back rest comprises:

-   -   two upwardly projecting vertical brackets which have their         bottom ends extending in the corner regions at the rear end of         the seat;     -   a crossbar connecting the two vertical brackets at their top         ends;     -   a backrest cover which can be pulled over the two vertical         brackets and the crossbar, and     -   tensioning strips which extend beyond the through-passage on the         upwardly oriented side of the seat and which are inserted in a         hem at the bottom end of the backrest cover.

BRIEF DESCRIPTION OF THE ACCOMPANYING DRAWINGS

In the drawings:

FIG. 1A shows a front view of a chair according to the invention with first-variant rear legs, that is to say without armrests;

FIG. 1B shows a side view of the chair according to FIG. 1A;

FIG. 1C shows an exploded illustration of the chair according to FIG. 1A;

FIG. 2A shows a front view of a chair according to the invention with second-variant rear legs, that is to say with armrests;

FIG. 2B shows a side view of the chair according to FIG. 2A;

FIG. 2C shows an exploded illustration of the chair according to FIG. 2A;

FIG. 3A shows a perspective view of a first-variant rear leg, that is to say without an armrest;

FIG. 3B shows a different perspective view of the rear leg according to FIG. 3A;

FIG. 4A shows a perspective view of a second-variant rear leg, that is to say with an armrest;

FIG. 4B shows a different perspective view of the rear leg according to FIG. 4A;

FIG. 4C shows the enlarged detail X2 from FIG. 4B in partial section;

FIG. 4D shows a vertical section through FIG. 4C taken along the length of the plug-in stub;

FIG. 4E shows a vertical section through FIG. 4C taken transversely to the plug-in stub;

FIG. 5A shows a partial vertical section of the docking region as the enlarged detail X1 from FIG. 1C;

FIG. 5B shows a vertical section through FIG. 2C taken transversely to the attachment part;

FIG. 5C shows the enlarged detail X3 from FIG. 5B with the inwardly extending conical narrowing;

FIG. 6A shows a second-variant rear leg, that is to say with an armrest, in partial section and in close proximity to the docking region according to FIG. 5A;

FIG. 6B shows the rear leg according to FIG. 6A in the docked state;

FIG. 7A shows a plan view, in perspective, of a second-variant rear leg with the top armrest part separated;

FIG. 7B shows the view from beneath of the top armrest part from FIG. 7A;

FIG. 7C shows a foam-filled top armrest part;

FIG. 8A shows a vertical longitudinal section through the armrest from FIG. 6A;

FIG. 8B shows the enlarged detail X4 from FIG. 8A;

FIG. 9A shows a partial lateral section of a chair according to the invention with second-variant rear legs, that is to say with armrests;

FIG. 9B shows the chair according to FIG. 9A with a seat cover;

FIG. 9C shows the enlarged detail X5 from FIG. 9A;

FIG. 9D shows the enlarged detail X6 from FIG. 9A;

FIG. 9E shows the enlarged detail X7 from FIG. 9B; and

FIG. 9F shows the enlarged detail X8 from FIG. 9B.

EXEMPLARY EMBODIMENT

A detailed description of an exemplary embodiment will be given hereinbelow, with reference to the accompanying drawings, in respect of the chair according to the invention.

The following applies to the rest of the description. If, in order to avoid ambiguity in the drawings, a figure contains designations which are not explained in the directly associated text of the description, then you are referred to the point at which they are mentioned in previous descriptions of the figures. For reasons of clarity, components are not usually designated again in subsequent figures, provided that it is clear from the drawings that they are “recurring” components.

FIGS. 1A to 1C

The body 1 comprises the horizontally arranged seat 11, the backrest 12, which has its vertical brackets 120,120′ extending at the rear end 110 of the seat 11, and the front legs 10,10′, which curve downward in the corner regions of the front end 111 of the seat 11 and extend to the floor. The backrest 12 is shaped ergonomically in accordance with the profile of the vertical brackets 120,120′, the latter, in the first instance, extending steeply upward, with a slight forward slant, from their bottom end 121,121′, then merging in a curved manner into a rearwardly inclined rectilinear section and, at their top ends 122,122′, extending rearward once again in a curved manner. A crossbar 123 connects the two vertical brackets 120,120′at the top.

In respect of its longitudinal axis, the chair has a mirror-inverted construction, so that the left-hand first-variant rear leg 2′, which is shown in this series of figures both in the mounted state on the body 1 and in the state in which it has been removed from the latter, is mirror-symmetrical in relation to the right-hand first-variant rear leg 2, which is only illustrated in the docked state. The leg supports 20,20′, which taper downward in the direction of their bottom ends 200,200′, merge in a curved manner at the top end into the curved connectors 21,21′, on which the plug-in stubs 22,22′, forming an obtuse angle with the leg supports 20,20′, extend. The outer surfaces of the plug-in stubs 22,22′ are provided with an outer toothing formation 220,220′. The seat 11 has two upwardly projecting lateral wall peripheries 112,112′. The seat 11 is bounded at the rear by an upwardly projecting rear wall periphery 113, the lateral wall peripheries 112,112′ merging into the rear wall periphery 113 in a curved transition region 114,114′, so that the seat 11 has a shell-like form.

The two attachment parts 14,14′ are arranged in the corner regions at the rear end 110 of the seat 11, where the lateral wall peripheries 112,112′ meet the rear wall periphery 113. The rear legs 2,2′ are docked on the body 1 in a form-fitting manner by virtue of the plug-in stubs 22,22′ being pushed into the openings 141 of the attachment parts 14,14′ and the plug-in stubs 22,22′ then being fastened on the attachment part 14,14′ be means of screws 19. Located at the front end 110 of the sear 11 is a unit-spaced rib formation 13 which comprises longitudinal ribs 130, which run between the lateral wall peripheries 112,112′, and transverse ribs 131, which are arranged perpendicularly to the longitudinal ribs. The unit-spaced rib formation 13 serves for fastening and anchoring a cushion 5 and also for reinforcing the seat 11.

The seat 11 is stabilized further by fitting a reinforcing insert 16, e.g. a sheet-metal plate, which is positioned on the unit-spaced rib formation 13, parallel to the longitudinal ribs 130 thereof and fastened on it by means of screws 19. The seat 11, which is thus stabilized in two ways, also withstands high loading without buckling. A through-passage 150 extends beneath a channel 15. In order to fasten the backrest cover 4 pulled over the backrest 12, tensioning strips 40 are inserted into the hem 41 at the bottom end of the backrest cover 4 and are then guided through the through-passage 150 from beneath and fastened on the channel 15 such that their two ends project out of the channel and extend beyond the through-passage 150. For height-levelling purposes, the bottom ends 100,100′ of the front legs 10,10′ are provided with front sliders 102 and the bottom ends 200,200′ of the rear legs 2,2′ are provided with rear sliders 202. In order to safeguard the surface on which the chair is placed, that side of the front slider 102 which is directed toward the floor is covered with a front piece of felt 103 and that side of the rear slider 202 which is directed toward the floor is covered with a rear piece of felt 203.

FIGS. 2A to 2C

The chair which is shown here differs from the chair which has been illustrated previously in FIGS. 1A to 1C merely by way of a different configuration of the rear legs 2,2′. The first-variant and second-variant rear legs 2,2′ are described in detail in the following FIGS. 3A to 4E.

FIGS. 3A to 4E

Both the first-variant rear legs 2,2′ and the second-variant rear legs 2,2′ each comprise a leg support 20,20′, a curved connector 21,21′ and a plug-in stub 22,22′. The leg supports 20,20′ extend upward from their bottom end 200,200′. The curved connector 21,21′ adjoins the top end 201,201′ of the leg supports 20,20′. The cross section of the leg supports 20,20′ is in the form of a rectangle with corners which are rounded to a pronounced extent, the width of those surfaces of the leg supports 20,20′ which, in the mounted state, run parallel to the side boundaries of the seat 11 increasing continuously upward, while the width of those surfaces of the leg supports 20,20′ which are oriented in the forward and rearward directions remains constant over the axial extent of the leg supports. At the top end 201,201′, the leg supports 20,20′ merge, at an obtuse angle, into the curved connectors 21,21′, of which the cross section flattens gradually in order, finally, to be elliptical at the transition between the curved connector 21,21′and the plug-in stub 22,22′.

The curved connector 22,22′ projects at an obtuse angle from the leg supports 20,20′. The plug-in stub 22,22′, which extends from the curved connector 21, 21′, has an elliptical cross section which tapers conically in the direction of the free end. The outer surface of the plug-in stubs 22,22′ is provided with an encircling outer toothing formation 220,220′ which comprises spaced-apart grooves arranged longitudinally in relation to the axis of the plug-in stubs 22,22′, this resulting in a cross-sectionally undulating contour of the outer toothing formation 220,220′. In order to reduce weight, the plug-in stub 22,22′ has an internal cavity 221 which, extending over the axial extent of the plug-in stub 22,22′, penetrates from the end side 224 of the latter into the curved connector 21,21′. Projecting from the inner surface of the cavity 221, inside the latter, is an elongate convexity 222 of oval cross section which runs parallel to the longitudinal axis of the plug-in stub 22,22′and contains a blind hole 223 which is accessible from the end side 224 of the plug-in stub 22,22′.

The second-variant rear legs 2,2′ are extended in relation to the first-variant rear legs 2,2′ by a connecting part 23,23′ which has its bottom end 230,230′ extending at the top end 201,201′ of the leg supports 20,20′, as a rectilinear continuation of the leg supports 20,20′. The top end 231 of the connecting parts 23,23′ is adjoined, at right angles, by the bottom armrest parts 24,24′, which are arranged horizontally when the rear legs 2,2′ are in the mounted state. The top armrest parts 3,3′ comprise a top longitudinal section 30,30′ which, in the mounted state, runs parallel to the lateral seat boundaries and, the rear, curves, at a slightly obtuse angle, into a top transverse section 31,31′. The bottom armrest parts 24,24′ comprise a bottom longitudinal section 240,240′, which is congruent with the top longitudinal section 30,30′, and a bottom transverse section 241,241′, which is congruent with the top transverse section 31,31′.

FIGS. 5A to 6B

The two attachment parts 14,14′ which are positioned on the seat 11, and are adjacent to the rear wall periphery 113, are of identical construction. They are in the form of a round housing with an opening 141, which is externally accessible from the side, and an outer contour which has an elliptical cross section narrowing eccentrically toward the rear wall periphery 113. The openings 141 open out, beneath the vertical brackets 120,120′ into the curved transition regions 114,114′ between lateral wall peripheries 112,112′ and the rear wall periphery 113. The openings 141 are bounded in the inward direction in each case by a rear wall 142 in which a screwhole 143 is provided. The elliptical cross sections of the openings 141 taper conically toward the rear wall 142 and correspond with the cross sections of the plug-in stubs 22,22′. The inner surface of the opening 141 is provided with an inner toothing formation 140,140′, which is designed to complement the outer toothing formation 220,220′ of the plug-in stub 22,22′.

When a rear leg 2,2′ is docked on the body 1 (see FIGS. 6A and 6B), in the first instance the plug-in stub 22′ is plugged into the opening 141 of the attachment part 14′. In this case, the outer toothing formation 220′ of the plug-in stub 22′ and the inner toothing formation 140′ of the attachment part 14′ mesh with one another, as a result of which the plug-in stub 22′is secured in a form-fitting manner against rotation. The mating toothing formations 220′,140′ result in a considerable increase in surface area, and thus in force distribution over a wide area, in order to control the torques acting in the plastic parts. At the same time, the blind hole 223 in the convexity 222 within the plug-in stub 22′ coincides with the screwhole 143 in the rear wall of the attachment part 14′. In a following step, in order to fasten the plug-in stub 22′, a screw 19 is guided through the screw-hole 143 and engages, behind the latter, into the internal thread of the blind hole 223.

FIGS. 7A to 8B

For the purposes of reducing weight and increasing cooling during production by injection molding, the bottom armrest part 24 is of shell-like design. In order that it is nevertheless sufficiently stable, bottom ribs 242 are provided internally for reinforcing purposes. The top armrest part 3, likewise of shell-like configuration, is reinforced by top ribs 32, which form the second interspaces 37 between them. The top armrest part 3 is filled with a foam material 36 which, during foaming, penetrates into the second interspaces 37 and is thus subdivided into units which are distributed uniformly within the top armrest part 3. The foam material 36 flows into the recesses 35 during foaming and, once it has set, is thus fastened on the top armrest part 3. The bottom armrest part 24 contains two upwardly projecting stubs 243 and the top armrest part 3 contains two housing-like plug-in structures 33 with stub holes 34 which correspond with the stubs 243. For fastening purposes, the top armrest part 3,3′ is positioned on the bottom armrest part 24,24′, in which case the stubs 243 penetrate into the stub holes 34 and are retained therein by a barb-like latching element 39. In order for the stub holes 34 to remain free during foaming of the foam material 36, a cover 38 is positioned on the housing 33.

FIGS. 9A to 9F

The cushion 5 is of sandwich-like construction. The cushion foam material 52 is introduced between a top sheet 51 and a bottom sheet 50. The bottom sheet 50 has a pattern of perforations 500 around the periphery and the top sheet 51 has a top pattern of perforations 510 around the periphery. During foaming, the cushion foam material 52 flows into the bottom and top patterns of perforation 500,510 in order, once set, to be fastened on the bottom and top sheets 50,51. A contour 501 which complements the attachment parts 14,14′ is formed in the surface of the top sheet 51 at the rear corners, which are adjacent to the attachment parts 14,14′ when the cushion 5 is in the inserted state. The attachment parts 14,14′ project from the seat 11 to some extent in the direction of the rear wall periphery 113, so that a gap remains between the seat 11 and attachment parts 14,14′. The corner regions of the top sheet 51 are pushed into this gap until the bottom sections of the attachment parts 14,14′ are embedded in the contour 501 of the top sheet 51. The bottom sheet 50 is foamed onto the seat and, in the process, flows into the first interspaces 132 formed by the longitudinal ribs and transverse ribs 130,131. In the set state, the bottom sheet 50 is secured by the longitudinal ribs 130, which project upward from the seat 11 with a slight forward slant, against displacement both rearward in the horizontal direction and in the vertical direction, while the transverse ribs 131 block the bottom sheet 50 against lateral displacement. 

1. A chair comprising: a) a single-part body (1) comprising: aa) a seat (11) arranged horizontally; ab) an upwardly projecting backrest (12) extending from the seat (11) at the rear; ac) front legs (10,10′) extending from the seat (11) to the floor at the front; and b) rear legs (2,2′) which are plugged into the body (1) and extend to the floor, wherein c) each rear leg (2,2′) is present as a separate component and is provided with a plug-in part (22,22′) which is not rotationally symmetrical; d) an externally accessible opening (141) into which the plug-in parts (22,22′) can be plugged in a form-fitting manner is present on a lateral portion of the body (1) in the region of the rear seat end (110); and e) the plug-in parts (22,22′) and openings (141) are provided with a surface area which is enlarged in relation to their core diameters.
 2. The chair as claimed in claim 1, wherein a) the plug-in part (22,22′) is designed as a plug-in stub (22,22′) which extends from the rear leg (2,2′) and is of elliptical cross section, the cross section of the plug-in stub (22,22′) tapering conically in the direction of the free end; b) the openings (141) have an elliptical cross section which complements the plug-in stubs (22,22′) and widens in the direction of the inlet of the openings (141); and c) the openings (141) are oriented toward the sides of the chair.
 3. The chair as claimed in claim 2, wherein a) on their outer surface, the plug-in stubs (22,22′) have an encircling outer toothing formation (220,220′) which extends in the axial direction of the plug-in stubs (22,22′) and openings (141); and b) on their inner surface, the openings (141) have an inner toothing formation (140,140′) which complements the outer toothing formation (220,220′) of the plug-in stubs (22,22′).
 4. The chair as claimed in claim 3, wherein a rear leg (2,2′) comprises: a) an elongate leg support (20,20′); b) a curved connector (21,21′) extending at the top end (201,201′) of the leg support (20,20′); and c) the plug-in stub (22,22′), which adjoins the curved connector (21,21′) and is arranged horizontally in the plugged-in state.
 5. The chair as claimed in claim 4, wherein the rear leg (2,2′) merges upward into an armrest (24,3; 24′,3′).
 6. The chair as claimed in claim 5, wherein a rear leg (2,2′) comprises: a) a connecting part (23,23′) which is designed as an extension of the leg support (20,20′) and has its bottom end (230,230′) extending at the top end (201,201′) of the leg support (20,20′); b) a bottom armrest part (24,24′) which is attached to the top end (231, 231′) of the connecting part (23,23′) and is arranged horizontally when the rear leg (2,2′) is in the plugged-in state; c) a separate, top armrest part (3,3′) being provided and being fastened on the bottom armrest part (24,24′).
 7. The chair as claimed in claim 6, wherein the seat (11) is of shell-like design and: a) has an upwardly projecting lateral wall periphery (112,112′) along each of its lateral boundaries; and b) has an upwardly projecting rear wall periphery (113) along its rear boundary; c) the lateral wall peripheries (112,112′) merge into the rear wall periphery (113) curved transition region (114,114′).
 8. The chair as claimed in claim 7, wherein a) arranged in the corner regions at the rear end (110), on the upwardly oriented side of the seat (11), are housing-like attachment parts (14,14′) which enclose the openings (141), which extend parallel to the rear wall periphery (113); b) the attachment parts (14,14′) are bounded by a rear wall (142) in the direction of the seat interior; c) the openings (141) open out into the transition regions (114,114′) between the lateral wall peripheries (112,112′) and the rear wall periphery (113); d) an externally accessible screwhole (143) is provided in the rear wall (142); e) the plug-in stubs (22,22′) have an internal cavity (221); f) projecting from the inner surface of the cavity (221) is a convexity (222) which is arranged longitudinally in relation to the axis of the plug-in stub (22,22′); and g) an internally threaded blind hole (223) is provided in the convexity (222), the blind hole (223) coinciding with the screwhole (143) in the rear wall (142) of the attachment part (14,14′) in the plugged-in state.
 9. The chair as claimed in claim 8, wherein the chair has: a) a unit-spaced rib formation (13) arranged at the front end (111) of the seat (11), on the upwardly oriented side thereof; the rib formation comprising: aa) spaced-apart longitudinal ribs (130) which are arranged parallel to the front boundary of the seat (11) and project upward with a forward slant; ab) spaced-apart transverse ribs (131) which are arranged transversely to the longitudinal ribs (130) and project upward from the seat (11); b) a sandwich-construction cushion comprising: ba) a bottom sheet (50) which is to be foamed onto the seat (11), extends between the lateral wall peripheries (112,112′), reaches, in the forward direction, beyond the unit-spaced rib formation (13) is adjacent, in the rearward direction, to the rear wall periphery (113) and, during foaming, flows into first interspaces (132) formed between the longitudinal ribs (130) and transverse ribs (131); bb) a top sheet (51) which is arranged parallel to the bottom sheet (50) and congruently therewith and, in the rear corner regions, has a respective contour, in the clearance between the attachment parts (14,14′) and seat (11), in which the attachment parts (14,14′) are embedded; and bc) a cushion foam material (52) which is introduced between the bottom sheet (50) and top sheet (51).
 10. The chair as claimed in claim 9, wherein the seat (11) has a through-passage (150) at the rear end, and the back rest (12) comprises: a) two upwardly projecting vertical brackets (120,120′) which have their bottom ends (121,121′) extending in the corner regions at the rear end (110) of the seat (11); b) a crossbar (123) connecting the two vertical brackets (120,120′) at their top ends (122,122′); c) a backrest cover (4) which can be pulled over the two vertical brackets (120,120′) and the crossbar (123), and d) tensioning strips (40) which extend beyond the through-passage (150) on the upwardly oriented side of the seat (11) and which are inserted in a hem (41) at the bottom end of the backrest cover (4). 